1. Field of the Invention
The present invention relates to a delivery vehicle that is moved by driving a servomotor, and a method and program to control driving of a delivery vehicle.
2. Description of the Related Art
There have been known vehicle control systems that automatically deliver goods using delivery vehicles, for example, in a factory or warehouse. In such a system, each delivery vehicle is driven by a servomechanism including a servomotor. The servomechanism includes a controller, a servo amplifier, and a servomotor. The servo amplifier drives the servomotor by supplying, to the servomotor, a drive current corresponding to the difference between the command position from the controller and the current position from a position detector in the servomotor. Japanese Unexamined Patent Application Publication No. 2000-99151 discloses, as such a system, a configuration in which the gain for feedback control varies with the weight of a loaded article.
When unexpected disturbance or the like occurs, the servomechanism may abruptly change the drive of the servomotor so that the current position follows the command position. However, such a transient movement for following the command position cannot be controlled by the controller. For this reason, the current position may significantly deviate from the command position due to the unexpected disturbance or the like, failing to follow the command position. Further, the servomechanism may raise the output torque in order to follow the command position, thereby increasing power consumption. Furthermore, such an excessive movement may impair safety. While the system of Japanese Unexamined Patent Application Publication No. 2000-99151 described above performs feedback control using an appropriate gain corresponding to the weight of a loaded article, the system does not have any means for avoiding the current position from excessively deviating from the command position.